Efficient haptic accuator

ABSTRACT

The current document is directed to non-linear haptic actuators that use a rotor, rotor-suspension, and spring subsystem to efficiently generate vibrational forces in various types of devices and appliances in which the non-linear haptic actuators are incorporated. Non-linear haptic actuators can be designed and manufactured to be more space efficient than unbalanced-electric-motor and linear-resonant vibration modules and, because most of the frictional forces produced in unbalanced-electric-motor and linear-resonant vibration modules are eliminated from non-linear haptic actuators, non-linear haptic actuators are generally more power efficient and robust than unbalanced-electric-motor and linear-resonant vibration modules.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims the benefit of Provisional Application No.62/509,644, filed May 22, 2017, which is incorporated by referenceherein in its entirety.

TECHNICAL FIELD

The current document is directed to vibration-generating devices and, inparticular, to vibration modules that can be incorporated into a widevariety of different types of electromechanical devices, appliances, andsystems to produce haptic signals, facilitate device operation, and forother purposes.

BACKGROUND

Vibration-inducing motors and mechanisms have been used for many yearsin a wide variety of different consumer appliances, toys, and otherdevices and systems. Examples include vibration signals generated bysmart phones and pagers, vibration-driven appliances, such ashair-trimming appliances, electric toy football games, and many otherappliances, devices, and systems. The most common electromechanicalsystem used for generating vibrations is an intentionally unbalancedelectric motor. While effective in producing vibrations, there are manyproblems associated with unbalanced-electric-motor vibration-generatingunits, including reliability issues and short useful lifetimes, poorpower efficiencies, constrained vibrational modes, and an inability toproduce varied vibrational forces and frequencies. Linear-resonantvibration modules (“LRVMs”) address certain of these problems, but arealso associated with problems and deficiencies, including spatialinefficiencies, non-optimal power-to-vibrational-force efficiencies, andmanufacturing challenges. Because of the above-discussed disadvantagesand problems associated with the commonly employed types ofvibration-generation units, designers, manufacturers, and, ultimately,users of a wide variety of different vibration-based devices,appliances, and systems continue to seek more efficient and capablevibration-generating units for incorporation into many consumerappliances, devices, and systems.

SUMMARY

The current document is directed to non-linear haptic actuators that usea rotor, rotor-suspension, and spring subsystem to efficiently generatevibrational forces in various types of devices and appliances in whichthe non-linear haptic actuators are incorporated. Non-linear hapticactuators can be designed and manufactured to be more space efficientthan unbalanced-electric-motor and linear-resonant vibration modulesand, because most of the frictional forces produced inunbalanced-electric-motor and linear-resonant vibration modules areeliminated from non-linear haptic actuators, non-linear haptic actuatorsare generally more power efficient and robust thanunbalanced-electric-motor and linear-resonant vibration modules.

In one aspect of the present disclosure, a non-linear haptic actuator isdisclosed.

In one embodiment thereof, the non-linear haptic actuator includes: ahousing; a moving component that moves relative to housing, the movingcomponent including: a rotor-weight subcomponent; a spring affixed to(i) an inner surface of the housing at a first end of the spring and(ii) the rotor-weight subcomponent at a second end of the spring; and arotor-weight-suspension subcomponent that suspends the rotor-weightsubcomponent within the housing; and an oscillation-drive component thatdrives the oscillation of the rotor-weight subcomponent.

In another embodiment, the non-linear haptic actuator includes: ahousing; and a moving component including: a mass component; a pluralityof springs each attached to (i) an inner surface of the housing at afirst end of the spring and (ii) the mass at a respective second end ofeach of the plurality of springs, the plurality of springs beingconfigured to collectively enable the mass component to oscillate alongan arc-shaped path at the respective second ends of the plurality ofsprings via alternating magnetic forces from a coil adjacent to the masscomponent to produce an unbalanced vibrational force; and a suspensioncomponent that suspends the mass component within the housing so as tofacilitate the oscillation of the mass component along the arc-shapedpath.

In another embodiment, the non-linear haptic actuator includes: at leastone mass; and at least one spring (i) affixed to a spring mount and (ii)coupled to the at least one mass at a second end of the at least onespring; wherein the at least one spring is configured to actuate the atleast one mass at the second of the at least one spring and remainstationary at the spring mount, the actuation of the at least one massincluding oscillation of the at least one mass between ends of a firstarc segment at the second of the at least one spring, the oscillationbeing caused by alternating magnetic forces from a coil, the coil beingdisposed proximate the at least one mass.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1A-B illustrate an unbalanced electric motor typically used forgenerating vibrations in a wide variety of different devices.

FIGS. 2A-B illustrate the vibrational motion produced by the unbalancedelectric motor shown in FIGS. 1A-B.

FIGS. 3A-G illustrate one particular LRVM, and operation of theparticular LRVM.

FIGS. 4A-D illustrate the general concept of the currently disclosednon-linear haptic actuator (“NLHA”).

FIGS. 5A-D illustrate space efficiency of an NLHA.

FIG. 6 illustrates an unbalanced rotor, rotor suspension, and springmechanism.

FIGS. 7A-8C illustrate one implementation of an unbalanced rotor, rotorsuspension, and spring mechanism used in the currently disclosed NLHA.

FIGS. 9A-D illustrate vibration modes in one implementation of thecurrently disclosed NLHA.

FIGS. 10A-C illustrate one implementation of the unbalanced rotor, rotorsuspension, and spring mechanism used in the currently disclosed NLHA.

FIGS. 11A-C illustrate a second implementation of the unbalanced rotor,rotor suspension, and spring mechanism used in the currently disclosedNLHA.

FIG. 12 illustrates one implementation of the currently disclosed NLHA.

DETAILED DESCRIPTION

FIGS. 1A-B illustrate an unbalanced electric motor typically used forgenerating vibrations in a wide variety of different devices. As shownin FIG. 1A, a small, relatively low-power electric motor 102 rotates acylindrical shaft 104 onto which a weight 106 is asymmetrically ormounted. FIG. 1B shows the weight asymmetrically mounted to the shaft,looking down at the weight and shaft in the direction of the axis of theshaft. As shown in FIG. 1B, the weight 106 is mounted off-center on theelectric-motor shaft 104. FIGS. 2A-B illustrate the vibrational motionproduced by the unbalanced electric motor shown in FIGS. 1A-B. As shownin FIGS. 2A-B, the asymmetrically-mounted weight creates an ellipticaloscillation of the end of the shaft, normal to the shaft axis, when theshaft is rotated at relatively high speed by the electric motor. FIG. 2Ashows displacement of the weight and shaft from the stationary shaftaxis as the shaft is rotated, looking down on the weight and shaft alongthe shaft axis, as in FIG. 1B. In FIG. 2A, a small mark 202 is providedat the periphery of the disk-shaped end the of electric-motor shaft toillustrate rotation of the shaft. When the shaft rotates at high speed,a point 204 on the edge of the weight traces an ellipsoid 206 and thecenter of the shaft 208 traces a narrower and smaller ellipsoid 210.Were the shaft balanced, the center of the shaft would remain at aposition 212 in the center of the diagram during rotation, but thepresence of the asymmetrically-mounted weight attached to the shaft, aswell as other geometric and weight-distribution characteristics of theelectric motor, shaft, and unbalanced weight together create forces thatmove the end of the shaft along the elliptical path 210 when the shaftis rotated at relatively high speed. The movement can be characterized,as shown in FIG. 2B, by a major axis 220 and minor axis 222 ofvibration, with the direction of the major axis of vibration equal tothe direction of the major axis of the ellipsoids, shown in FIG. 2A, andthe length of the major axis corresponding to the amplitude of vibrationin this direction. In many cases, the path along which the end of theshaft moves is closer to a circle than an ellipse, but, for purposes ofillustration, the eccentricity of the elliptical path is greatlyexaggerated, in FIG. 2A.

In many applications, in which a linear oscillation is desired,designers seek to force the major-axis-amplitude/minor-axis-amplituderatio to be as large as possible, but, because the vibration is producedby a rotational force, it is generally not possible to achieve linearoscillation. In many cases, the path traced by the shaft center may beclose to circular. The frequency of vibration of the unbalanced electricmotor is equal to the rotational frequency of the electric-motor shaftand is therefore constrained by the rate at which the motor can rotatethe shaft. At low rotational speeds, little vibration is produced. Asmentioned above, unbalanced electric motors generally have relativelyshort useful lifetimes and cannot be used to produce ranges ofvibrational forces and frequencies desired for many applications.

Various types of linear-resonant vibration modules (“LRVMs”) arecurrently used to generate vibrational forces in various different typesof appliances, devices, and systems. The linear nature of LRVMvibration-inducing motion allows certain of the problems associated withunbalanced-electric-motor vibrators, discussed above, to be addressed.An oscillating linear motion does not produce destructive forces thatquickly degrade and wear out an unbalanced electric motor. A linearlyoscillating mechanism is characterized by parameters that can bestraightforwardly varied in order to produce vibrations of a desiredamplitude and frequency over a very broad region of amplitude/frequencyspace. Linear oscillation within a LRVM translates into highly directionvibrational forces produced by an appliance or device that incorporatesthe LRVM.

FIGS. 3A-G illustrate one particular LRVM, and operation of theparticular LRVM. FIGS. 3A-G all use the same illustration conventions,next discussed with reference to FIG. 3A. The LRVM includes acylindrical housing 302 within which a solid, cylindrical mass 304, orweight, can move linearly along the inner, hollow, cylindrically shapedchamber 306 within the cylindrical housing or tube 302. The weight is amagnet, in certain implementations, with polarity indicated by the “+”sign 310 on the right-hand end and the “−” sign 312 on the left-hand endof the weight 304. The cylindrical chamber 306 is capped by two magneticdisks 314 and 316 with polarities indicated by the “+” sign 318 and the“−” sign 319. The disk-like magnets 314 and 318 are magneticallyoriented opposite from the magnetic orientation of the weight 304, sothat when the weight moves to either the extreme left or extreme rightsides of the cylindrical chamber, the weight is repelled by one of thedisk-like magnets at the left or right ends of the cylindrical chamber.In other words, the disk-like magnets act much like springs, tofacilitate deceleration and reversal of direction of motion of theweight and to minimize or prevent mechanical-impact forces of the weightand the end caps that close off the cylindrical chamber. Finally, a coilof conductive wire 320 girdles the cylindrical housing, or tube 302 atapproximately the mid-point of the cylindrical housing.

FIGS. 3B-G illustrate operation of the LRVM shown in FIG. 3A. When anelectric current is applied to the coil 320 in a first direction 322, acorresponding magnetic force 324 is generated in a direction parallel tothe axis of the cylindrical chamber, which accelerates the weight 304 inthe direction of the magnetic force 324. When the weight reaches a pointat or close to the corresponding disk-like magnet 314, as shown in FIG.3C, a magnetic force due to the repulsion of the disk-like magnet 314and the weight 304, 326, is generated in the opposite direction,decelerating the weight and reversing its direction. As the weightreverses direction, as shown in FIG. 3D, current is applied in anopposite direction 330 to the coil 320, producing a magnetic force 332in an opposite direction from the direction of the magnetic force shownin FIG. 3B, which accelerates the weight 304 in a direction opposite tothe direction in which the weight is accelerated in FIG. 3B. As shown inFIG. 3E, the weight then moves rightward until, as shown in FIG. 3F, theweight is decelerated, stopped, and then accelerated in the oppositedirection by repulsion of the disk-like magnet 316. An electricalcurrent is then applied to the coil 320 in the same direction 334 as inFIG. 3B, again accelerating the solid cylindrical mass in the samedirection as in FIG. 3B. Thus, by a combination of a magnetic field withrapidly reversing polarity, generated by alternating the direction ofcurrent applied to the coil, and by the repulsive forces between theweight magnet and the disk-like magnets at each end of the hollow,cylindrical chamber, the weight linearly oscillates back and forthwithin the cylindrical housing 302, imparting a direction force at theends of the cylindrical chamber with each reversal in direction.

There are many types and configurations of LRVMs, includingimplementations that include a disk-shaped spring and a disk-shapedvoice coil under a disk-shaped moving mass to which drive magnets areaffixed. In other implementations, the coil is printed on a printedcircuit board and drives a cylindrical moving mass back and forth in adirection orthogonal to the plane of the printed circuit board.

As discussed above, while often better suited for haptic applicationsthan unbalanced electric motors, LRVMs nonetheless associated with avariety of deficiencies and problems. In many applications, LRVMs aredimensionally awkward, having dimensions along the linear-oscillationaxis significantly greater than along dimensions orthogonal to thataxis, resulting in challenges in fitting the LRVMs into devices andapplications in which miniaturization is a major goal. LRVMs producelinear oscillation that is useful in many applications, but in thoseapplications in which more general vibrational patterns are desired,multiple LRVMs may be needed, further exacerbating space-efficiencyproblems associated with LRVMs. LRVMs, such as the LRVM described aboveand illustrated in FIGS. 3A-G, include surfaces that are in contact withone another and that, during oscillation, move relative to one another,creating significant amounts of friction, in turn decreasing theefficiency in power-to-vibrational-force conversion by LRVMs andrepresenting a significant source of wear and tear, dust and vaporgeneration, and heat generation.

The current document is directed to a new type of vibration-generationmodule that addresses the deficiencies and problems of unbalancedelectric motors and LRVMs, discussed above. FIGS. 4A-D illustrate thegeneral concept of the currently disclosed non-linear haptic actuator(“NLHA”). A NLHA, viewed from an exterior vantage point, appears to be asimple housing, such as the housing 402 shown in FIG. 4A. In FIG. 4A,the housing is cylindrically shaped, but housings of various differenttypes of shapes, from rectangular box-like shapes to various types ofasymmetric-cross-section cylinders and even irregular shapes may be usedin different applications for different purposes. FIGS. 4B-C illustratea moving element within the housing. In FIG. 4B, the moving element 404is in a centered position, with arrow 406 indicating the direction inwhich the moving element is currently moving. In FIG. 4C, the movingelement 408 has reached an extreme position to the left of the centeredposition shown in FIG. 4B and begins to move in the opposite direction,indicated by arrow 410. In FIG. 4D, the moving element has reached anextreme position to the right of the center position shown in FIG. 4Band begins to move back towards the center position, as indicated byarrow 412. The moving element 404 therefore oscillates back-and-forthalong an arc that subtends the angle θ 414, shown in FIG. 4D. It is forthis reason that the vibration module 402 is referred to as beingnon-linear. The moving element have various different shapes and sizes.As discussed below, for efficiency, the moving element is suspendedwithin the housing so that the moving element oscillates along an arcwithout contacting the housing and withoutrigid-surface-to-rigid-surface contacts with components of the NLHAother than the suspension subsystem, removing most of the frictionalforces inherent in unbalanced-electric-motor and linear resonantvibration modules.

FIGS. 5A-D illustrate space efficiency of an NLHA. FIGS. 5A-B representa view, from a top-down perspective, of an NLHA similar to the NLHAshown in FIGS. 4B-D. In FIG. 5A, a wedge-shaped moving element 502 isshown at the left-most extreme position and, in FIG. 5B, thewedge-shaped moving element 502 is shown at the right-most extremeposition. The wedge-shaped moving element 502 rotates about a centralpoint 504 and oscillates along an arc that subtends the angle θ 506,which has the numeric value π/2 for the example shown in FIG. 5A. Point506 within the wedge-shaped moving element, for example, rotates from afirst position shown in FIG. 5A to the second position shown in FIG. 5Bduring the clockwise motion of the first part of one oscillation cycle.Given that the radius of the housing has the numeric value 6 (508 inFIG. 5 A), the total area of the disk-shaped cross-section of thehousing is 36π, the area of the wedge-shaped moving element, or rotor,is 9π, and the area occupied by the rotor during back-and-forthoscillation is 18π (510 in FIG. 5A. Integrating the mass of each pointin the wedge-shaped moving element times the distance traveled by thepoint during the clockwise motion in one oscillation cycle, illustratedin FIGS. 5A-B, as indicated by expression 512 in FIG. 5B, provides anumerical value, 177.653, representing the total mass displacementduring a forward rotation corresponding to one half of an oscillationperiod. When the thickness of the wedge-shaped moving element, or rotor,has a numeric value 3 (514 in FIG. 5C), the computed mass displacementis 532.96 and the computed volume occupied by the rotor is 169.65 (516in FIG. 5C). As shown in FIG. 5D, similar moving-massive volumes can beobtained for rectangular-cross-section 520 and circular-cross-section522 LRVMs. However, as discussed above, the LRVMs use springs at eachend of the linear oscillation path, significantly increasing the lengthof the LRVM and generally increasing the dimensional asymmetry of theLRVM. Furthermore, the oscillation path may need to be significantlylengthened in order to increase the time during which the magnetic forcecan be applied to the moving mass in order to generate sufficientvelocity of the moving mass, since acceleration of the moving mass issignificantly inhibited by frictional forces. As discussed below, in thecurrently disclosed implementation of the NLHA, the rotor does notcontact the housing, as a result of which most of the frictional forcesassociated with moving the rotor are eliminated. Provided that thespring mechanism for the NLHA can be space-efficiently packaged withinthe housing, the NLHA can be significantly more compactly designed andmanufactured than an LRVM that produces similar vibrational forces.

FIG. 6 illustrates an unbalanced rotor, rotor suspension, and springmechanism. The rotor 602 is suspended in air, above a surface, such asthe bottom of the housing, by a first spring 604 and a second spring606. Each spring is securely attached to the rotor, at one end, andsecurely attached to a spring mount 608-609, at the other end. Spring604, for example, is securely attached to spring mount 608, at one end,and to the rotor 602 at the other end. Spring 606 is attached to therotor, at one end, and to spring mount 609, at the other end. The widthsof the two springs are each less than half the width of the rotor, sothat they can be vertically stacked, as shown in FIG. 6, with adequateremaining clearance between spring 604 and the underlying surface andbetween spring 604 and spring 606. During oscillation, discussed below,the two springs do not contact one another, so that, unlike in an LRVM,there are no surface-to-surface contacts producing frictional forces.Because the rotor is asymmetric with respect to a circle that includesan arc-shaped path along with the rotor oscillates, as discussed below,the rotor oscillation produces unbalanced vibrational forces and therotor, rotor suspension, and spring mechanism is referred to as being“unbalanced.”

The Bendix flex pivot has a configuration reminiscent of the rotor,rotor suspension, and spring mechanism illustrated in FIG. 6. The Bendixflex pivot, typically used in low-friction hinges, has been used in avariety of different electromechanical devices. However, in theseapplications, the Bendix flex pivot is generally balanced and designedto minimize vibration and, most importantly, the rotor is mechanicallycoupled to a linkage through which mechanical forces are imparted toadditional moving components of the devices. As farther discussed below,the currently disclosed NLHA employs a rotor, rotor suspension, andspring mechanism is unbalanced and designed to maximize vibrationalforces produced by oscillation of the rotor. Furthermore, the Bendixflex pivot is generally not designed for resilience to the types ofvibrational force produced by the currently disclosed rotor, rotorsuspension, and spring mechanism, discussed below with reference to FIG.7A-8C.

FIGS. 7A-8C illustrate one implementation of an unbalanced rotor, rotorsuspension, and spring mechanism used in the currently disclosed NLHA.In the unbalanced rotor, rotor suspension, and spring mechanismillustrated in FIG. 6, the crossover point between the two springs liesat the center of a circle through the centers of the curved rotor andthe two spring mounts. By contrast, as shown in FIG. 7A, in analternative configuration, the rotor, rotor suspension, and springmechanism features a crossover point 702 of the two springs 704 and 705that is significantly lowered towards the two spring mounts 706-707.Thus, the distance 708 from the crossover point 702 to arc 710connecting the two spring mounts, a, may be significantly smaller thanthe distance 712 between the rotor 714 and the crossover point 702, b.However, in yet additional implementations, a may be greater than orequal to b. The ratio a/b is one design parameter that can be adjustedto alter the operational characteristics and behaviors of an NLHA. Anoff-center crossover point may introduce additional asymmetry, or lackof balance, in an unbalanced rotor, rotor suspension, and springmechanism used in certain implementations of the currently disclosedNLHA that may contribute to production of desired vibrational forces. Inmany implementations, the arc-shaped path along which the rotor movessubtends an angle of between 30° and 70°, but larger and smaller anglesmay be achieved by varying design and implementation parameters.

As shown in FIG. 7B, the rotor, rotor suspension, and spring mechanismused in the currently disclosed NLHA employs springs with a verydifferent profile than those encountered in a typical Bendix flex pivot.In the Bendix flex pivot, the springs have rectangular profiles, withtwo pairs of parallel edges. By contrast, in the rotor, rotorsuspension, and spring mechanism used in the currently disclosed NLHA,each spring 720 has an asymmetric profile that includes a pair ofapproximately parallel edges 722-723 of different lengths, a longer edge724 orthogonal to the pair of approximately parallel edges, and a fourthedge 726 with a relatively long curved section 728 and a short linearsection 730. The currently employed springs with asymmetric profilesprovide greater strength and resilience with respect to the large forcesimparted to the springs during rotor oscillation. Again, there are manydifferent possible asymmetric spring profiles, but the springs used inthe currently disclosed NLHA are characterized by asymmetric shapes thatmove concentrated oscillation-induced stress away from the edge 722proximal to the spring mount and distribute the stress more uniformlyacross the spring, increasing operational resilience and robustness.

FIGS. 8A-C illustrate an unbalanced rotor, rotor suspension, and springmechanism used in the currently disclosed NLHA. In FIG. 8A, the threeillustrated rotor positions 802-804 corresponding to moving-elementpositions 408, 406, and 414, respectively, shown in FIGS. 4B-C. As canbe seen in FIG. 8A, the rotor oscillates in an arc about the crossoverpoint 806 of the two springs. FIG. 8B illustrates the two arcs 810-11over which the left-hand and right-hand ends of the rotor, respectively,oscillate. FIG. 8C shows a perspective view of the rotor, rotorsuspension, and spring mechanism 820 employed in the currently disclosedNLHA using the same illustration conventions used in FIG. 6.

FIGS. 9A-D illustrate vibration modes in one implementation of thecurrently disclosed NLHA. In FIG. 9A, the configuration of the rotor,rotor suspension, and spring mechanism used in the currently disclosedNLHA is illustrated using illustration conventions similar to those usedin FIGS. 8A-B. Points 902 and 904 represent the centers of the springmounts viewed top-down. Points 906 and 908 represent points at which aline coincident with the spring edges intersect and are inscribedthrough the rotor. During oscillation of the rotor, the average forcesgenerated by the rotor are represented by the three vectors 910-912.Vectors 910 and 911 are tangent to the arc over which the rotoroscillates while vector 912 points outward from the spring crossoverpoint 914 towards the center of the rotor when the rotor is in thecentered position shown in FIG. 8A. Vector 910 represents the forcegenerated when the rotor reaches the extreme position 802 shown in FIG.8A and reverses direction while vector 911 represents the forcegenerated when the rotor reaches the extreme position 804 shown in FIG.8A and reverses direction. Vector 912 represents the apparentcentrifugal force generated as the rotor moves along the arc, equal andopposite to the centripetal force exerted by the springs to constrainmotion of the rotor along the arc. As shown in FIG. 9B, vector 910 andvector 911 can each be resolved into a pair of vectors, one vector ofeach pair parallel to vector 912 and the other vector of each pairorthogonal to vector 912. Following straightforward vector addition ofthe vectors parallel to vector 912 and vector 912, the three resolvedforce vectors 914-916 are produced, as shown in FIG. 9C. These representthe directions of the time-averaged vibrational modes generated byoscillation of the rotor over an arc about the crossover point of thetwo springs. The vibrational forces produced by the NLHA oscillate backand forth along a line segment parallel to vectors 914 and 915 and, inaddition, oscillate up and down along the line segment parallel tovector 916. In general, as shown in FIG. 9C, the primary vibrationalmode is parallel to the line segment coincident with vectors 914 and915, while the secondary vibrational mode is orthogonal to the primaryvibrational mode. Different configurations, relative component weights,and other variations of the rotor, rotor suspension, and springmechanism used in the currently disclosed NLHA may produce differentrelative magnitudes of the vibrational forces produced along the twovibrational modes.

FIG. 9D illustrates the vibrational forces produced by the currentlydisclosed NLHA. In FIG. 9D, axis 902 represents time, axis 904represents the primary vibrational mode, and access 906 represents thesecondary vibrational mode. The amplitude of the primary vibrationalmode is shown to be significantly greater than that of the secondaryvibrational mode in FIG. 9D. Furthermore, the period of the primaryvibrational mode is one half the period of the secondary vibrationalmode. The secondary vibrational mode produces a maximal force, at points910-915, when the primary vibrational mode produces minimal forces. Ofcourse, the amplitudes, periods, and other parameters of the vibrationalforces generated by the currently disclosed NLHA depend on theconfiguration, component weights, spring constants of the springs, andother such parametric characteristics of the rotor, rotor suspension,and spring mechanism. In general, because of the elimination of themajority of frictional forces from the NLHA rotor, rotor suspension, andspring mechanism, the NLHA is characterized by relatively highpeak-height-to-peak-width vibrational-force ratios and efficientconversion of power to vibrational force.

FIGS. 10A-C illustrate one implementation of the unbalanced rotor, rotorsuspension, and spring mechanism used in the currently disclosed NLHA.FIG. 10A illustrates the rotor suspension and spring mechanism, alongwith oscillation-drive components, but without the rotor masses. The twosprings with asymmetric profiles 1002 and 1004 are mounted on springmounts 1006 and 1008, respectively, and are coupled to a platform 1010onto which wedge-shaped rotor weights are mounted, as discussed below.Two permanent magnets, including permanent magnet 1012, are mounted atthe edge of the platform 1012 to the top and bottom surfaces of theplatform or to the rotor weights. A coil 1014 is independently mountedin the position shown in FIG. 10A to provide alternating magnetic forcesto drive oscillation of the rotor, in similar fashion to the drivingcomponents of the LRVM, discussed above with reference to FIGS. 8A-B.FIG. 10B shows the rotor, rotor suspension, and spring mechanism withmounted wedge-shaped rotor weights, including top rotor weight 1016 andlower rotor weight 1018. FIG. 10C shows a top-down view of the rotor,rotor suspension, and spring mechanism.

FIGS. 11A-C illustrate a second implementation of the unbalanced rotor,rotor suspension, and spring mechanism used in the currently disclosedNLHA. In this implementation, the coil 1102 that drives oscillation ofthe rotor is independently mounted within a channel 1104 between twoparts 1106 and 1108 of the top rotor weight. The permanent magnets 1110and 1112 are incorporated into the 2 portions of the top rotor weight1106 and 1108. There are, of course, many additional variations andconfigurations that can be used to generate many additionalimplementations of the rotor, rotor suspension, and spring mechanismused in the currently disclosed NLHA.

FIG. 12 illustrates one implementation of the currently disclosed NLHA.In this implementation, the unbalanced rotor, rotor suspension, andspring mechanism 1202 is incorporated within a rectangular box-likehousing 1104. The two springs 1106 and 1108 are welded or otherwisepermanently affixed to the inner surface of a vertical wall 1110 of thehousing. A microprocessor 1112 is mounted on the floor of the housing,below the rotor, rotor suspension, and spring mechanism. Input signallines 1114 provide power and control instructions to the microprocessor,and the microprocessor controls transmission of current with alternatingpolarities to the coil, discussed above with reference to FIGS. 10A-11C,to drive rotor oscillation. In addition, a small permanent magnet 1116is mounted to the top of the wedge-shaped rotor weight, the position ofwhich is continuously monitored by a sensor 1118 that provides arotor-position signal 1120 to the microprocessor that the microprocessoruses to adjust control of the rotor, rotor suspension, and springmechanism to produce desired oscillation frequencies and desiredvibrational forces.

The present invention has been described in terms of particularembodiments, it is not intended that the invention be limited to theseembodiments. Modifications within the spirit of the invention will beapparent to those skilled in the art. For example, although thecurrently disclosed NLHA can be implemented in many differentdimensional ranges, many implementations are designed to have dimensionson the order of millimeters to one or a few centimeters. In theabove-discussed implementations, permanent magnets are mounted to orwithin the rotor, but, in alternative implementations, electromagnetsmay be used, powered through the metallic springs. Currentimplementations provide oscillation frequencies in the 100 to 130 Hzrange, but, by changing the configuration, dimensions, spring materials,component weights, and other such parameters, oscillation frequenciesfrom below 20 Hz to greater than 250 Hz may be achieved. In currentimplementations, driving currents of around 30 mA at 3 V are employed,with around 10 ms start times and 50 ms start times, although, as withother parameters, these parameters may vary depending on the variousabove-mentioned design parameters. In current implementations, thesprings are fabricated from a beryllium-copper alloy, but other types ofspring materials are used in alternative implementations, includingother types of metal alloys, a titanium alloy, as well as various typesof composite and polymeric materials, silicon, graphene andcarbon-nanotube containing materials, and other flexible materials thatprovide sufficient rigidity to suspend the rotor within the housing. Incertain implementations, each spring may include two or more layers ofthe same or different compositions fused together by welding or variouslayer-annealing processes. In general, the frequency range of an NLHAand the magnitude of the vibrational forces produced by the NLHA greatlydepend on the dimensions and composition of the springs. In alternativeimplementations, a printed circuit board housing floor may includeprinted coils to drive oscillation of the rotor. A variety ofsophisticated feedback-controlled control programs may be executed bythe microprocessor included within, or external to, the housing togenerate a wide variety of different types of vibrational responses fromthe NLHA, including various types of vibrational patterns that changeover time, vibration responses that maximize vibrational forces, andother types of vibrational responses. Any of many different materialscan be used for the rotor weights, with the materials generally selectedbased on density as well as resilience to deterioration or shape changeduring rotor oscillation.

The invention claimed is:
 1. A non-linear haptic actuator comprising: ahousing; a moving component that moves relative to housing, the movingcomponent comprising: a rotor-weight subcomponent; a spring affixed to(i) an inner surface of the housing at a first end of the spring and(ii) the rotor-weight subcomponent at a second end of the spring, thespring being configured to enable the rotor-weight subcomponent tooscillate along an arc-shaped path at the second end of the spring viaalternating magnetic forces from a coil subcomponent to produce anunbalanced vibrational force, the coil subcomponent being adjacent tothe second end of the spring; and a rotor-weight-suspension subcomponentthat suspends the rotor-weight subcomponent within the housing so as tofacilitate the oscillation of the rotor-weight subcomponent along thearc-shaped path; and an oscillation-drive component that drives theoscillation of the rotor-weight subcomponent, the oscillation-drivecomponent comprising the coil subcomponent and a magnet subcomponent,one of the coil and magnet subcomponents being incorporated within themoving component, and the other one of the coil and magnet subcomponentsbeing external to the moving component.
 2. The non-linear hapticactuator of claim 1 wherein arc-shaped path subtends an angle of between30° and 70°.
 3. The non-linear haptic actuator of claim 1 wherein themoving component comprises a second spring, and therotor-weight-suspension subcomponent is coupled to the spring and thesecond spring, each of the spring and the second spring having anasymmetric profile.
 4. The non-linear haptic actuator of claim 3 whereinthe asymmetric profile comprises a first pair of parallel edges shorterthan the edges of a second pair of edges, the first pair of paralleledges including a mounting edge and a rotor edge, the mounting edgelonger than the rotor edge, and the second pair of edges including afirst substantially linear edge and a second edge that includes asubstantially linear segment parallel to the first edge of the secondpair of edges and a longer curved segment.
 5. The non-linear hapticactuator of claim 4 wherein each of the spring and the second springcomprises one of: a single layer composed of a beryllium-copper alloy, ametal alloy that includes titanium, a metal alloy other than aberyllium-copper alloy and a metal alloy that includes titanium, acomposite material, a polymeric material, graphene and carbon-nanotubecontaining materials, and silicon; and two or more fused layers.
 6. Thenon-linear haptic actuator of claim 4 wherein the asymmetric profileserves to move stress concentrations away from the mounting edge of thespring and distribute stress within the spring.
 7. The non-linear hapticactuator of claim 4 wherein the mounting edge of each of the spring andthe second spring is proximal to an attachment location on the housingor a spring mount attached to the housing, and the rotor edge of each ofthe spring and the second spring is proximal to the rotor-weightsubcomponent.
 8. The non-linear haptic actuator of claim 7 wherein therotor edge of each of the spring and the second spring is coupled to aplatform-like planar rotor-weight mount.
 9. The non-linear hapticactuator of claim 8 wherein two rotor-weight portions are mounted toeach side of the platform-like planar rotor-weight mount.
 10. Thenon-linear haptic actuator of claim 8 wherein the oscillation-drivecomponent comprises: the magnet subcomponent having one or more rotormagnets incorporated within, or attached to, one or more of therotor-weight subcomponent and the rotor-weight-suspension subcomponent;and the coil subcomponent having a coil that generates a magnetic fieldwhen current passes through the coil.
 11. The non-linear haptic actuatorof claim 10 wherein the coil is suspended in an arc-shaped channel withthe rotor-weight subcomponent, and the one or more rotor magnets aredisposed adjacent to each side of the coil.
 12. The non-linear hapticactuator of claim 10 wherein the coil is disposed adjacent to a curvedface of the rotor-weight subcomponent, in which one or more rotormagnets are incorporated or to which the one or more rotor magnets areaffixed.
 13. The non-linear haptic actuator of claim 10 wherein the oneor more rotor magnets comprise one or more of: permanent magnets; andelectromagnets.
 14. The non-linear haptic actuator of claim 1 furthercomprising: a microprocessor; control signal lines; and a power-inputline.
 15. The non-linear haptic actuator of claim 14 wherein themicroprocessor executes one or more control routines that controltransmission of current with alternating polarities to the coil to driveoscillation of the rotor-weight subcomponent.
 16. The non-linear hapticactuator of claim 14 wherein the non-linear haptic actuator furtherincludes an additional permanent magnet affixed to, or incorporatedwithin, the rotor-weight subcomponent, and a magnetic sensor mounted tothe housing, the magnetic sensor being configured to output arotor-position signal indicative of a position of the rotor-weightsubcomponent to the microprocessor, the microprocessor being configuredto use the rotor-position signal to drive oscillation of therotor-weight subcomponent to a specified frequency, to produce one ormore specified vibrational forces, or to produce more complex vibrationpatterns.
 17. The non-linear haptic actuator of claim 14 whereinoperational parameters are specified to the microprocessor through thecontrol signal lines.
 18. The non-linear haptic actuator of claim 14wherein the microprocessor is mounted to a printed circuit boardparallel to a floor of the housing.
 19. The non-linear haptic actuatorof claim 14 wherein the microprocessor is mounted externally to thehousing.
 20. The non-linear haptic actuator of claim 1 wherein thenon-linear haptic actuator is incorporated into an electronic device,appliance, or system to provide haptic signals to a user of theelectronic device, appliance, or system.